Synthesis,spectral characterization,and antimicrobial studies of metal complexes of the Schiff base derived from [4-amino-N-guanylbenzene sulfonamide] and salicylaldehyde

Sulfaguanidinesalicylaldimine is a good bacteriostatic and a good complexing agent. Schiff-base complexes of Cu(II), Ni(II), Co(II), Zn(II), Cd(II), VO(IV), and UO₂(VI) have been synthesized. The structural features of the complexes have been confirmed by microanalytical data, FAB mass, IR, UV-Vis, ¹H-NMR, and EPR spectra. Molar conductance indicates the presence of nonelectrolytes. Spectroscopic and other analytical studies reveal the square-planar geometry for copper, square-pyramidal geometry for oxovanadium, seven-coordinate UO₂(VI) complex, and octahedral geometry for other complexes. The EPR spectrum of the copper complex in the powdered form at 77 K was recorded. The redox behavior of the copper and oxovanadium complexes was studied using cyclic voltammetry. Antimicrobial activities of the compounds have been studied against microorganisms such as Escherichia coli, Staphylococcus aureus, and Candida by well-diffusion technique in DMSO. Some of the complexes have higher activity than the free ligand and the standard.     

Spectrofluorimetric Determination of Trace Amounts of Gallium with Salicylaldehyde Benzoylhydrazone

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Piperidine–iodine a dual system catalyst for synthesis of coumarin bearing pyrrolo[1,2-a]quinoxaline derivatives via a one-pot three-component reaction

The synthesis of 3-(4-alkyl-4,5-dihydropyrrolo[1,2-a]quinoxalin-4-yl)-2H-chromen-2-one derivatives by a three-component reaction of salicylaldehyde, β-keto esters, and 1-(2-aminophenyl)pyrrole using piperidine–iodine as a dual system catalyst is reported. Good yields, mild reaction conditions, and ease of handling are the main aspects of the method. The structural assignments are supported by ¹H NMR, ¹³C NMR, and X-ray crystallography data.     

l-Proline catalyzed efficient and convenient synthesis of substituted 2H-chromenes by three-component reaction

A convenient and efficient method is described for the synthesis of alkoxy substituted 2H-chromens by l-proline catalyzed reaction of salicylaldehydes with diketone in alcohol. The method is applicable for various substituted salicylaldehydes and aliphatic as well as benzylic alcohols.     

Chemoselective Route for Synthesis of N‐Aryl‐3‐oxochromeno[2,3‐c]pyrazole‐2(3H)‐carbothioamide Derivatives

A chemoselective route for the synthesis of chromeno[2,3‐c]pyrazole‐2(3H)‐carbothioamide derivatives by a five‐component reaction of salicylaldehyde, malononitrile, NH₂NH₂?H₂O, aryl isothiocyanate, and H₂O in EtOH/AcOH mixture is reported. This new protocol has the advantages of high yields, short reaction times, ease of operation, and simple purification. All structures were confirmed by IR, ¹H‐ and ¹³C‐NMR, and MS analyses. A plausible mechanism for this type of reaction is proposed (Scheme 2).     

Facile and Mild Synthesis and Characterization of Some New Diazo Dyes on the Basis of Schiff Bases in the Presence of Nanocrystalline Magnesium Oxide as a Base Catalyst under Solvent‐free Conditions

In this research, some new diazo dyes including Schiff base have been synthesized by the condensation reaction between ethylenediamine and derivatives of salicylaldehyde containing diazo functional groups in the presence of nanocrystalline magnesium oxide as a solid base catalyst under solvent‐free conditions. Nanocrystalline magnesium oxide has been characterized by XRD, BJH and TEM techniques. The corresponding products have been obtained in excellent yields and high purity. All of the obtained diazo‐Schiff bases are highly colored and can be applicable as useful diazo dyes and characterized by spectroscopy data.     

Determination of boron in water samples at nanograms per cubic decimeter levels by reversed-phase partition high-performance liquid chromatography with precolumn complexation reaction using salicylaldehyde and 1-amino-8-naphthol-3,6-disulfonate

A new method for the highly sensitive and selective determination of boron at nanograms per cubic decimeter levels has been developed based on the derivatization reaction of boron using salicylaldehyde and 1-amino-8-naphtol-3,6-disulfonate with reversed-phase partition high-performance liquid chromatography. A detection limit as low as 2.0 nmol/dm³ (22 ng/dm³) was achieved without any preconcentration. No significant interference was observed in the determination of 16 μmol/dm³ of boron with the addition of nine metal ions (Al^III, Cu^II, Co^II, Fe^II, Fe^III, Ni^II, Mn^II, V^V, Zn^II) at concentrations 100 times greater than that of boron without any masking procedure. The proposed method was successfully applied to the determination of boron in river water, tap water, doubly distilled water, and highly purified water. Figure Scheme of formation of boron-azomethine-H complex with salicylaldehyde and 1-amino-8-naphthol-3, 6-disulfonate     

Komplexe von Vanadium und Titan mit Salicylaldehyd-benzoylhydrazon und 2-(2′-Hydroxyphenyl)-chinolin-8-ol. Kristallstruktur von μ-Oxo-bis[oxo{2-(2′-Hydroxyphenyl)-chinolin-8-olato(2-)}-vanadium(V)]

Complexes of Vanadium and Titanium with Salicylaldehyde benzoylhydrazone and 2-(2′-Hydroxyphenyl)-8-quinolinol. Crystal Structure of μ-Oxo-bis[oxo{2-(2′-hydroxyphenyl)-8-quinolinato(2-)}-vanadium(V)] . By reaction of titanium(IV)-isopropoxide and bis(acetylacetonato)-oxovanadium(IV) with salicylaldehyde benzoylhydrazone and 2-(2′hydroxyphenyl)-8-quinolinol, respectively, the metal complexes of the tridentate diacidic ligands were synthesized and characterized mass spectrometrically. The mass spectra of the titanium compounds correspond to the expected bisligand complexes whereas several species are demonstrable in the case of vanadium. Crystals of μ-oxo-bis[oxo{2-(2′-hydroxyphenyl)-8-quinolinolato(2-)}-vanadium(V)] were isolated and characterized by X-ray structural analysis. The complex exhibits C₂ symmetry, accordingly the μ₂-oxygen atom is situated on the 4 axis. The VOV bridge is angular with the unusually small bond angle of 107.3°. The coordination polyhedron is distorted octahedral. The compound additionally contains one molecule of chloroform per formula unit which is disordered in two positions. Crystallographic data see “Inhaltsübersicht”.     

N-邻羟苄基氨基酸的合成、表征及抑菌活性

将水杨醛、溴代水杨醛及二溴代水杨醛分别与4种L-α-氨基酸进行缩合反应生成相应席夫碱,不经分离直接加硼氢化钠将其还原制得N-邻羟苄基氨基酸类化合物(3)。 化合物的结构经IR、¹H NMR和元素分析测试技术表征确认。 测得化合物3在质量分数为0.05%时,对金黄色葡萄球菌的抑菌率为100％,对白色念珠菌有较强的抑菌活性,对大肠杆菌有一定的抑菌活性。 氨基酸的碳链R的结构是影响化合物抑菌活性的关键因素,不同烷基R对白色念珠菌和大肠杆菌抑菌活性增强的顺序为CH(CH₃)₂＞CH₃,CH₂CH(CH₃)₂＞H,苯环上引入溴原子对目标化合物的抑菌活性影响不明显。